Adaptive tractor wheel

ABSTRACT

Provided are tractor wheels for a downhole tractor. An example tractor wheel comprises a series of continuous springs disposed on the circumference of the tractor wheel, wherein the individual continuous springs in the series of continuous springs are separated by a gap, and a void disposed on the interior of the tractor wheel and that is continuous about the circumference of the tractor wheel.

TECHNICAL FIELD

The present disclosure relates to tractor wheels for wellbore conduits,and more particularly, to an adaptive tractor wheel capable of deformingand adapting to the surface of a wellbore conduit to improve tractionand preserve the integrity of the surface of the conduit.

BACKGROUND

In horizontal or deviated sections of a wellbore, the conveyance oftubing and wireline tools may be difficult because gravity may not berelied upon to assist in propelling the tubing or wireline tool as isdone in vertical sections of a wellbore. In the horizontal or deviatedsections of the wellbore, the tubing or wireline tool may become lodgedin the wellbore preventing forward progress. This may occur from contactfriction with an adjacent surface or from buckling/coiling of thewireline or tubing.

Downhole tractors may be used to facilitate the conveyance of wirelineassemblies and tubing in the horizontal or deviated sections of thewellbore. Downhole tractors engage the inner walls of a wellbore conduit(e.g., the casing, tubing, piping, or the wellbore wall of an open-holeportion of the wellbore). The downhole tractor may be used to propel anyportion of a tubing or a wireline connected thereto to a desiredlocation in the wellbore.

The downhole tractor uses wheels to propel itself along the adjacentcontact surface of the conduit with which it is engaged. These wheelshave to maintain traction with the adjacent contact surface in order topropel the tubing or wireline in the conduit. If the tractor wheel doesnot maintain sufficient traction to propel the tubing or wireline, itmay slip. If slippage occurs, more pressure may be applied to thetractor wheel against the contact surface to reduce slippage of thetractor wheel. However, adding pressure to the tractor wheel may shortenthe life of the tractor wheel and may damage the contact surface of theconduit due to the high stress applied at this area of the conduit.Damaging the surface of the conduit may reduce the integrity of thesurface of the conduit over time. For example, leaks and cracks maydevelop in the damaged surface of the conduit. In some extremeinstances, damage to the surface of the conduit could result in failureof the conduit. Moreover, the increasing stress at the contact surfaceof the tractor wheel results in a faster rate of wheel degradation. Thismay necessitate replacing tractor wheels more frequently.

Failure to reduce slippage and/or minimize the damage to the surface ofthe conduit can result in an increase in non-productive time as well asin operation expenditures for subsequent operations.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative examples of the present disclosure are described in detailbelow with reference to the attached drawing figures, which areincorporated by reference herein, and wherein:

FIG. 1A is an illustration of an orthogonal view of an example tractorwheel in accordance with one or more examples described herein;

FIG. 1B is another illustration of an orthogonal view of the exampletractor wheel of FIG. 1A, except that the illustration of FIG. 1B isrotated 90° along line A-A of the illustration of FIG. 1A in accordancewith one or more examples described herein;

FIG. 1C is an illustration of an isometric view of the example tractorwheel of FIGS. 1A and 1B in accordance with one or more examplesdescribed herein;

FIG. 2 is an illustration of a cross-section of the example tractorwheel of FIGS. 1A-1C in accordance with one or more examples describedherein;

FIG. 3A is an illustration of an orthogonal view of another exampletractor wheel in accordance with one or more examples described herein;

FIG. 3B is another illustration of an orthogonal view of the exampletractor wheel of FIG. 3A, except that the illustration of FIG. 3B isrotated 90° along line D-D of the illustration of FIG. 3A in accordancewith one or more examples described herein;

FIG. 3C is an illustration of an isometric view of the example tractorwheel of FIGS. 3A and 3B in accordance with one or more examplesdescribed herein;

FIG. 4 is an illustration of a cross-section of the example tractorwheel of FIGS. 3A-3C in accordance with one or more examples describedherein;

FIG. 5A is an illustration of an orthogonal view of another exampletractor wheel in accordance with one or more examples described herein;

FIG. 5B is another illustration of an orthogonal view of the exampletractor wheel of FIG. 5A, except that the illustration of FIG. 5B isrotated 90° along line C-C of the illustration of FIG. 5A in accordancewith one or more examples described herein;

FIG. 5C is an illustration of an isometric view of the example tractorwheel of FIGS. 5A and 5B in accordance with one or more examplesdescribed herein;

FIG. 6A is an illustration of an isometric view of an example tractortread fitted on to the tractor wheel of FIGS. 1A-2 in accordance withone or more examples described herein; FIG. 6B is an illustration of anorthogonal view of the example tractor tread of FIG. 6A fitted on to thetractor wheel of FIGS. 1A-2 in accordance with one or more examplesdescribed herein;

FIG. 7A is an illustration of an isometric view of an example tractortread fitted on to the tractor wheel of FIGS. 1A-2 in accordance withone or more examples described herein; FIG. 7B is an illustration of anorthogonal view of the example tractor tread of FIG. 7A fitted on to thetractor wheel of FIGS. 1A-2 in accordance with one or more examplesdescribed herein;

FIG. 8 is an illustration of a schematic of an example downholetractoring system comprising an example of a downhole tractor inaccordance with one or more examples described herein.

The illustrated figures are only exemplary and are not intended toassert or imply any limitation with regard to the environment,architecture, design, or process in which different examples may beimplemented.

DETAILED DESCRIPTION

The present disclosure relates to tractor wheels for wellbore conduits,and more particularly, to an adaptive tractor wheel capable of deformingand adapting to the surface of a wellbore conduit to improve tractionand preserve the integrity of the surface of the conduit.

In the following detailed description of several illustrative examplesreference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration specific examples that maybe practiced. These examples are described in sufficient detail toenable those skilled in the art to practice them, and it is to beunderstood that other examples may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the disclosed examples. Toavoid detail not necessary to enable those skilled in the art topractice the examples described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the illustrative examples are defined only by the appendedclaims.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the present specification and associated claims areto be understood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained by the examples of the present invention. At thevery least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claim, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques. It should be noted that when “about” is at the beginning ofa numerical list, “about” modifies each number of the numerical list.Further, in some numerical listings of ranges some lower limits listedmay be greater than some upper limits listed. One skilled in the artwill recognize that the selected subset will require the selection of anupper limit in excess of the selected lower limit.

Unless otherwise specified, any use of any form of the terms “connect,”“engage,” “couple,” “attach,” or any other term describing aninteraction between elements is not meant to limit the interaction todirect interaction between the elements and may also include indirectinteraction between the elements described. Further, any use of any formof the terms “connect,” “engage,” “couple,” “attach,” or any other termdescribing an interaction between elements includes items integrallyformed together without the aid of extraneous fasteners or joiningdevices. In the following discussion and in the claims, the terms“including” and “comprising” are used in an open-ended fashion, and thusshould be interpreted to mean “including, but not limited to.” Unlessotherwise indicated, as used throughout this document, “or” does notrequire mutual exclusivity.

The terms uphole and downhole may be used to refer to the location ofvarious components relative to the bottom or end of a well. For example,a first component described as uphole from a second component may befurther away from the end of the well than the second component.Similarly, a first component described as being downhole from a secondcomponent may be located closer to the end of the well than the secondcomponent.

Examples of the methods and systems described herein relate to anadaptive tractor wheel capable of deforming and adapting to the surfaceof a wellbore conduit. Advantageously, the tractor wheel improvestraction at the contact surface of the conduit. This improved tractionmay result in reduced slippage of the downhole tractor. Further, thetractor wheel deforms to better grip the surface of the conduit. Assuch, the footprint of the tractor wheel may increase as it adapts tothe surface of the conduit. Adaptively increasing the footprint of thetractor wheel may result in a relative reduction of the overall pressureneeded to sufficiently grip the contact surface of the conduit. Thisadvantage may result in improving the longevity of the tractor wheel andminimizing damage to the surface of the conduit.

FIG. 1A is an illustration of an orthogonal view of an example tractorwheel 5. The tractor wheel 5 comprises a series of curved continuoussprings 10 disposed along the circumference of the tractor wheel 5. Theindividual continuous springs 10 are separated by gaps 15. FIG. 1B isanother illustration of an orthogonal view of the example tractor wheel5, except that the illustration of FIG. 1B is rotated 90° along line A-Aof the illustration of FIG. 1A. FIG. 1B further illustrates an inset toenlarge the illustration of the gap 15. FIG. 1C is an illustration of anisometric view of the example tractor wheel 5. Each of the continuoussprings 10 is positioned around the circumference of the tractor wheel 5and are curved along the width of the tractor wheel 5. The gaps 15separate the individual continuous springs 10 along the circumferenceand also extend along the width of the tractor wheel 5. The separationof the individual continuous springs 10 allows for the individualelastic deformation of each continuous spring 10. The continuous springs10 may elastically deform when pressure is applied, and then they mayregain their illustrated default shape after said pressure is removed.FIG. 2 is an illustration of a cross-section of the example tractorwheel 5. As illustrated, the continuous springs 10 are disposed on theexterior of the tractor wheel 5. On the interior of tractor wheel 5 isdisposed a series of discontinuous springs 20, the series extendinggenerally around the circumference of the tractor wheel 5 similarly tothe continuous springs 10. Although not visible from this perspective,the individual discontinuous springs 20 in the series are also separatedfrom each other by gap 15. The discontinuous springs 20 are noted asbeing discontinuous in that there is an additional gap, illustrated asgap 25, which bifurcates the discontinuous springs 20, therebyseparating each discontinuous spring 20 into two independent membersthat face each other across gap 25. This inner series of discontinuoussprings 20 are disposed on the interior of the tractor wheel 5, and theexterior continuous springs 10 may engage these interior discontinuoussprings 20 for additive stiffness if a higher pressure is applied.

Separating the exterior continuous springs 10 from the interiordiscontinuous springs 20 is a void 30. Void 30 extends along thecircumference of the tractor wheel 5 and provides a void space in whichthe continuous springs 10 may be displaced when they are elasticallydeformed under pressure. Inward of the discontinuous springs 20 is anadditional void 35. The void 35 provides a void space in which thediscontinuous springs 20 may be displaced when they are elasticallydeformed under pressure. In some alternative examples, void 35 may notcomprise a void space, but instead may comprise a filler material havinga sufficient shape memory. The filler material may comprise a rubberand/or a rubber and metal composite. The metal may be a metal alloy. Forexample, the rubber and metal composite may comprise a rubber havingmetal particulates distributed throughout to increase the stiffness ofthe rubber. In another example, the rubber and metal composite maycomprise a continuous and/or discontinuous wire mesh having rubberembedded and distributed throughout. Any material having a desiredstiffness and shape memory may be used as a filler material for void 35.With the benefit of this disclosure, one of ordinary skill in the artwill be readily able to select an appropriate filler material for thevoid 35.

Hub 40 is disposed at the center of the tractor wheel 5. Hub 40 may becoupled to an axle (not illustrated) extending through the axis of thetractor wheel 5. Tractor wheel 5 may then be able to rotate about theaxle.

The tractor wheel 5 may comprise any material sufficient for the desiredapplications of tractor wheel 5. For example, tractor wheel 5 maycomprise such materials including, but not limited to, a rubber, arubber and metal composite, or any combination thereof. With the benefitof this disclosure, one of ordinary skill in the art will be readilyable to select an appropriate material for the tractor wheel 5 toperform a desired operation.

It should be clearly understood that the example of tractor wheel 5illustrated by FIGS. 1A-2 is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIGS. 1A-2 as described herein.

FIG. 3A is an illustration of an orthogonal view of another exampletractor wheel 100. The tractor wheel 100 comprises a series of curvedcontinuous springs 10 disposed along the circumference of the tractorwheel 100 analogous to the series of curved continuous springs 10described above with respect to example tractor wheel 5 as illustratedin FIGS. 1A-2 . The individual continuous springs 10 are separated bygaps 15. The gaps 15 are analogous to the gaps 15 described above withrespect to example tractor wheel 5 as illustrated in FIGS. 1A-2 . FIG.3B is another illustration of an orthogonal view of the example tractorwheel 100, but the illustration of FIG. 3B is rotated 90° along line D-Dof the illustration of FIG. 3A. FIG. 3C is an illustration of anisometric view of the example tractor wheel 100.

FIG. 4 is an illustration of a cross-section of the example tractorwheel 100. Tractor wheel 100 is similar to the tractor wheel 5illustrated in FIGS. 1A-2 except that tractor wheel 100 does notcomprise a series of discontinuous springs. Disposed on the interior ofthe tractor wheel 100 is a void 105. Void 105 extends along thecircumference of the tractor wheel 100 and provides a void space in theinterior of tractor wheel 100 in which the continuous springs 10 may bedisplaced when they are elastically deformed under pressure. In somealternative examples, void 105 may not comprise a void space, butinstead may comprise a filler material having a sufficient shape memory.The filler material may comprise a rubber and/or a rubber and metalcomposite. The metal may be a metal alloy. For example, the rubber andmetal composite may comprise a rubber having metal particulatesdistributed throughout to increase the stiffness of the rubber. Inanother example, the rubber and metal composite may comprise acontinuous and/or discontinuous wire mesh having rubber embedded anddistributed throughout. Any material having a desired stiffness andshape memory may be used as a filler material for void 105. With thebenefit of this disclosure, one of ordinary skill in the art will bereadily able to select an appropriate filler material for the void 105.

Hub 40 is disposed at the center of the tractor wheel 100. Hub 40 may becoupled to an axle (not illustrated) extending through the axis of thetractor wheel 100. The tractor wheel 100 may then be able to rotateabout the axle.

The tractor wheel 100 may comprise any material sufficient for thedesired applications of tractor wheel 100. For example, tractor wheel100 may comprise such materials including, but not limited to, a rubber,a rubber and metal composite, or any combination thereof. With thebenefit of this disclosure, one of ordinary skill in the art will bereadily able to select an appropriate material for the tractor wheel 100to perform a desired operation.

It should be clearly understood that the example of tractor wheel 100illustrated by FIGS. 3A-4 is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIGS. 3A-4 as described herein.

FIG. 5A is an illustration of an orthogonal view of an example tractorwheel 200. The tractor wheel 200 comprises a series of curved wiresprings 205 disposed along the circumference of the tractor wheel 200.The wire springs 205 are separated by gaps 210. FIG. 5B is anotherillustration of an orthogonal view of the example tractor wheel 200, butthe illustration of FIG. 5B is rotated 90° along line C-C of theillustration of FIG. 5A. As can be viewed from this perspective, thewire springs 205 comprise two subtypes distinguished by whether they arefixed to a body 215 of the tractor wheel 200 or whether they hang freeof attachment to the body 215 of the tractor wheel 200. Wire springs205A are not coupled to the body 215 of the tractor wheel 200 and areallowed to hang free of it. Wire springs 205B may be coupled to the body215 of the tractor wheel 200. For example, the wire springs 205B may bewelded or coupled via a threaded connection to the body 215. The wiresprings 205B may be continuous and independently comprise a loop passingthrough the body 215 at the coupling point. Alternatively, the wiresprings 205B may be discontinuous and be connected to the body 215 atthe point of separation. The wire springs 205A are discontinuous and areseparated at the portion which hangs free of the body 215 as illustratedin FIG. 2C. FIG. 2C is an illustration of an isometric view of theexample tractor wheel 200. Each of the wire springs 205 is positionedaround the circumference of the tractor wheel 200 and is curved alongthe width of the tractor wheel 200. Gaps 210 separate the individualwire springs 205 along the circumference and also extend along the widthof the tractor wheel 200. The separation of the individual wire springs205 allows for the individual elastic deformation of each wire spring205. The wire springs 205 may elastically deform when pressure isapplied, and then they may regain their illustrated default shape aftersaid pressure is removed.

With continued reference to FIG. 5C, disposed on the interior of thewire springs 205 is a void 220. Void 220 extends along the circumferenceof the tractor wheel 200 and provides a void space into which the wiresprings 205 may be displaced when they are elastically deformed underpressure. In some alternative examples, void 220 may not comprise a voidspace, but instead may comprise a filler material having a sufficientshape memory. The filler material may comprise a rubber and/or a rubberand metal composite. The metal may be a metal alloy. For example, therubber and metal composite may comprise a rubber having metalparticulates distributed throughout to increase the stiffness of therubber. In another example, the rubber and metal composite may comprisea continuous and/or discontinuous wire mesh having rubber embedded anddistributed throughout. Any material having a desired stiffness andshape memory may be used as a filler material for void 220. With thebenefit of this disclosure, one of ordinary skill in the art will bereadily able to select an appropriate filler material for the void 220.

With reference to FIGS. 5B and 5C, hub 40 is disposed at the center ofthe tractor wheel 200. Hub 40 may be coupled to an axle (notillustrated) extending through the axis of the tractor wheel 200. Thetractor wheel 200 may then be able to rotate about the axle.

The tractor wheel 200 may comprise any material sufficient for a desiredapplication of tractor wheel 200. For example, tractor wheel 200 maycomprise such materials including, but not limited to, a rubber, arubber and metal composite, or any combination thereof. With the benefitof this disclosure, one of ordinary skill in the art will be readilyable to select an appropriate material for the tractor wheel 200 toperform a desired operation.

It should be clearly understood that the example of tractor wheel 200illustrated by FIGS. 5A-5C is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIGS. 5A-5C as described herein.

Another aspect of tractor wheel design is the pattern of the tread. Thetread design may affect the size of the contact surface of the tractorwheel, the traction of the tractor wheel, the ability of the tractorwheel to displace debris in the path of the tractor wheel, and/or thedegree of damage the tractor wheel may impart to the conduit. Forexample, if a tread does not provide sufficient surface area at thecontact surface, the tractor wheel may slip. As another example, if thetread has sharp edges or teeth it may damage the surface of the conduitby making impressions or divots in the surface of the conduit.

FIG. 6A is an illustration of an isometric view of an example tractortread 300 fitted on to a tractor wheel 5 as illustrated in FIGS. 1A-2 .FIG. 6B is an illustration of an orthogonal view of an example tractortread 300 fitted on to a tractor wheel 5 as illustrated in FIGS. 1A-2 .Tractor tread 300 comprises a series of alternating forward-facingraised curves 305 and backward-facing raised curves 310. The terminalends of each forward-facing raised curve 305 is disposed in the openbend of each adjacent backward-facing raised curve 310. The terminalends of each backward-facing raised curve 310 is disposed in the openbend of each adjacent forward-facing raised curve 305. As such, themirror image forward-facing raised curves 305 and the backward-facingraised curves 310 are slightly offset from each other as illustrated.Although the forward-facing raised curves 305 and backward-facing raisedcurves 310 are illustrated as generally having a C-shape and an inverseC-shape respectively, it is to be understood that the degree ofcurvature can vary as desired. Debris paths 315 are flow paths for thedisplacement of debris which may occur in the path of the tractor wheel5. In some optional examples, the edges of the forward-facing raisedcurves 305 and the backward-facing raised curves 310 may be tapered fromthe base to the tip. All or a portion of the edges may be tapered. Forexample, only the edges of the terminal ends of the forward-facingraised curves 305 and the backward-facing raised curves 310 may betapered. As another example, every edge of the forward-facing raisedcurves 305 and the backward-facing raised curves 310 may be tapered. Asillustrated by FIGS. 6A and 6B, the forward-facing raised curves 305 andthe backward-facing raised curves 310 do not comprise sharp points oredges and as such, may prevent or reduce damage to the conduit surfaceand may prolong the life of the tractor wheel 5 as sharp points andedges may wear at a greater rate relative to tread patterns comprisingblunted edges.

Although FIGS. 6A and 6B illustrate tractor tread 300 as used withtractor wheel 5, it is to be understood that tractor tread 300 may beused on any tractor wheel (e.g., tractor wheel 100 and tractor wheel 200as were illustrated in FIGS. 3A-5C), as well as any other tractor wheel,whether or not described herein.

The tractor tread 300 may comprise any material sufficient for a desiredapplication of the tractor tread 300. For example, tractor tread 300 maycomprise such materials including, but not limited to, a rubber, arubber and metal composite, or any combination thereof. With the benefitof this disclosure, one of ordinary skill in the art will be readilyable to select an appropriate material for the tractor tread 300 toperform a desired operation.

It should be clearly understood that the example of tractor tread 300illustrated by FIGS. 6A and 6B is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIGS. 6A and 6B as describedherein.

FIG. 7A is an illustration of an isometric view of another exampletractor tread 400 fitted on to a tractor wheel 5, as illustrated inFIGS. 1A-2 . FIG. 7B is an illustration of an orthogonal view of anexample tractor tread 400 fitted on to the tractor wheel 5, asillustrated in FIGS. 1A-2 . Tractor tread 400 comprises a continuousserpentine-shaped raised curve 405 with raised posts 410 disposed ineach open bend. The degree of curvature of the serpentine-shape can varyas desired. In some optional examples, the edges of theserpentine-shaped raised curve 405 and the raised posts 410 may betapered from the base to the tip. All or a portion of the edges may betapered. As illustrated by FIGS. 7A and 7B, the serpentine-shaped raisedcurve 405 and the raised posts 410 do not comprise sharp points or edgesand as such, may reduce the damage to the conduit surface and mayprolong the life of the tractor wheel 5.

Although FIGS. 7A and 7B illustrate tractor tread 400 as used withtractor wheel 5, it is to be understood that tractor tread 400 may beused on any tractor wheel (e.g., the tractor wheel 100 and the tractorwheel 200 that were illustrated in FIGS. 3A-5C), as well as any othertractor wheel, whether or not described herein.

The tractor tread 400 may comprise any material sufficient for a desiredapplication of tractor tread 400. For example, the tractor tread 400 maycomprise such materials including, but not limited to, a rubber, arubber and metal composite, or any combination thereof. With the benefitof this disclosure, one of ordinary skill in the art will be readilyable to select an appropriate material for the tractor tread 400 toperform a desired operation.

It should be clearly understood that the example of tractor tread 400illustrated by FIGS. 7A and 7B is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIGS. 7A and 7B as describedherein.

FIG. 8 illustrates a schematic of an example downhole tractoring system500 comprising an example of a downhole tractor 505. Downhole tractor505 comprises a tractor wheel 510 as described herein. For example,tractor wheel 510 may comprise any of tractor wheel 5, tractor wheel100, and/or tractor wheel 200 as described in FIGS. 1A-5C. Moreover, thetractor wheel 510 may comprise a tractor tread as described herein. Forexample, tractor wheel 510 may comprise tractor tread 300 and/or tractortread 400 as described in FIGS. 6A-7B. The downhole tractor 505 isoperable at a variety of speed/force combinations during a tractoringrun into and through the illustrated wellbore 515. Although threetractor wheels 510 are illustrated in FIG. 8 , the downhole tractor 505may include more or less wheels, as appropriate. One or more wheels maybe powered by wheel assemblies for propelling the downhole tractor 505through the wellbore 515 in order to run a wireline 520 into thewellbore 515. Other tractor wheels 510 or wheel assemblies of thedownhole tractor 505 may not be powered but instead may be freelyrotatable in contact with the conduit 525 during operation of thedownhole tractor 505.

The illustrated downhole tractoring system 500 includes the downholetractor 505 coupled to a length of wireline 520 and positioned in aconduit 525 (e.g., a casing) disposed within wellbore 515. Theillustrated wellbore 515 is a deviated wellbore that is formed to extendfrom the surface 530 to a subterranean formation 535 (e.g., ahydrocarbon bearing geologic formation) and includes a vertical portion540, a heel 545, a horizontal portion 550, and a toe (not illustrated).Although portions 540 and 550 are referred to as “vertical” and“horizontal,” respectively, it should be appreciated that such wellboreportions may not be exactly vertical or horizontal, but instead may besubstantially vertical or horizontal to account for drilling operations.Further, the wellbore 515 may be cased as illustrated or may be anuncased open hole. The wellbore 515 may comprise both cased and uncasedregions. The conduit 525 may be a casing, an open hole portion of thewellbore 515, any type of workstring, any type of tubing, etc.

Wireline 520 extending from the surface 530 to the downhole tractor 505may be used to conduct electrical power and control signals to and fromthe downhole tractor 505 via a single-strand or a multi-strand conductor555 that is run through the wireline 520 downhole to the downholetractor 505. In some examples, the wireline 520 may be an electricalcable to lower tools (e.g., the downhole tractor 505 and/or otherdownhole tools) into the wellbore 515 and to facilitate the transmissionof power and data. The wireline 520, in some examples, may be aconductor for electric logging and cables incorporating electricalconductors.

In the illustrated example, the downhole tractor 505 is coupled to adownhole tool 560, which may be, for example, a shifting tool, a loggingtool, an explosive tool (e.g., a perforating gun or otherwise), apacker, or any other type of downhole tool or other payload.

The illustrated wireline 520 is connected to a surface/control system565 provided to perform a variety of control and data acquisitionfunctions, such as controlling the power supply to the downhole tractor505, receiving and determining forces acting on the downhole tractor 505sensed by one or more sensors in the downhole tractor 505, andretrieving and displaying data obtained by various sensors in thedownhole tractor 505.

Although FIG. 8 describes the use of a downhole tractor 505 to convey awireline downhole, it is to be understood that the examples andprinciples of the disclosure described herein are also applicable toother types of downhole conveyance methods and systems. For example, thedownhole tractor 505 may be used to convey tubing, for example, coiledtubing into laterals and other wellbores so as to prevent buckling ofthe coiled tubing.

It should be clearly understood that the example downhole tractoringsystem 500 illustrated by FIG. 8 is merely a general application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited in any manner to the details of FIG. 8 as described herein.

It is to be recognized that the disclosed tractor wheels and methods ofuse thereof may directly or indirectly affect the various downholeequipment and tools that may contact the tractor wheels disclosedherein. Such equipment and tools may include, but are not limited to,wellbore casing, wellbore liner, completion string, insert strings,drill string, coiled tubing, slickline, wireline, drill pipe, drillcollars, mud motors, downhole motors and/or pumps, surface-mountedmotors and/or pumps, centralizers, turbolizers, scratchers, floats(e.g., shoes, collars, valves, etc.), logging tools and relatedtelemetry equipment, actuators (e.g., electromechanical devices,hydromechanical devices, etc.), sliding sleeves, production sleeves,plugs, screens, filters, flow control devices (e.g., inflow controldevices, autonomous inflow control devices, outflow control devices,etc.), couplings (e.g., electro-hydraulic wet connect, dry connect,inductive coupler, etc.), control lines (e.g., electrical, fiber optic,hydraulic, etc.), surveillance lines, drill bits and reamers, sensors ordistributed sensors, downhole heat exchangers, valves and correspondingactuation devices, tool seals, packers, cement plugs, bridge plugs, andother wellbore isolation devices, or components, and the like. Any ofthese components may be included in the methods and systems generallydescribed above and depicted in FIGS. 1A-8 .

Provided are tractor wheels for a downhole tractor in accordance withthe disclosure and the illustrated FIGS. An example tractor wheelcomprises a series of continuous springs disposed on the circumferenceof the tractor wheel, wherein the individual continuous springs in theseries of continuous springs are separated by a gap, and a void disposedon the interior of the tractor wheel and that is continuous about thecircumference of the tractor wheel.

Additionally or alternatively, the tractor wheel may include one or moreof the following features individually or in combination. The tractorwheel may further comprise a series of discontinuous springs disposed onthe interior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother. The void may be filled with a filler material comprising arubber, a rubber and metal composite, or any combination thereof. Thevoid may be a first void; and wherein the tractor wheel furthercomprises a second void disposed between the series of continuoussprings and the series of discontinuous springs. The first void may befilled with a filler material comprising a rubber, a rubber and metalcomposite, or any combination thereof. The tractor wheel may furthercomprise a series of discontinuous springs; wherein the individualcontinuous springs in the series of continuous springs alternate withthe individual discontinuous springs in the series of discontinuoussprings; wherein at least a portion of the continuous springs arecoupled to a body of the tractor wheel. The tractor wheel may furthercomprise a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in the open bend of each adjacent backward-facing raised curve;wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.The tractor wheel may further comprise a tread comprising a continuousserpentine-shaped raised curve with raised posts disposed in each openbend.

Provided are methods for tractoring in a wellbore in accordance with thedisclosure and the illustrated FIGS. An example method comprisesproviding a downhole tractor comprising a tractor wheel comprising: aseries of continuous springs disposed on the circumference of thetractor wheel, wherein the individual continuous springs in the seriesof continuous springs are separated by a gap, and a void disposed on theinterior of the tractor wheel and that is continuous about thecircumference of the tractor wheel; introducing the downhole tractorinto the wellbore; and propelling the downhole tractor in the wellbore.

Additionally or alternatively, the method may include one or more of thefollowing features individually or in combination. The tractor wheel mayfurther comprise a series of discontinuous springs disposed on theinterior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother. The void may be filled with a filler material comprising arubber, a rubber and metal composite, or any combination thereof. Thevoid may be a first void; and wherein the tractor wheel furthercomprises a second void disposed between the series of continuoussprings and the series of discontinuous springs. The first void may befilled with a filler material comprising a rubber, a rubber and metalcomposite, or any combination thereof. The tractor wheel may furthercomprise a series of discontinuous springs; wherein the individualcontinuous springs in the series of continuous springs alternate withthe individual discontinuous springs in the series of discontinuoussprings; wherein at least a portion of the continuous springs arecoupled to a body of the tractor wheel. The tractor wheel may furthercomprise a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in the open bend of each adjacent backward-facing raised curve;wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.The tractor wheel may further comprise a tread comprising a continuousserpentine-shaped raised curve with raised posts disposed in each openbend. The wellbore may comprise a conduit; wherein the tractor wheelcontacts the surface of the conduit; wherein the conduit comprises anopen hole portion of the wellbore, a casing, or a tubing. The tractorwheel may further comprise a series of discontinuous springs disposed onthe interior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother; wherein the void is a first void; and wherein the tractor wheelfurther comprises a second void disposed between the series ofcontinuous springs and the series of discontinuous springs. The tractorwheel may further comprise a series of discontinuous springs; whereinthe individual continuous springs in the series of continuous springsalternate with the individual discontinuous springs in the series ofdiscontinuous springs; and wherein at least a portion of the continuoussprings are coupled to a body of the tractor wheel. The void may befilled with a filler material comprising a rubber, a rubber and metalcomposite, or any combination thereof. The tractor wheel may furthercomprise a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in the open bend of each adjacent backward-facing raised curve;and wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.The tractor wheel may further comprise a tread comprising a continuousserpentine-shaped raised curve with raised posts disposed in each openbend.

Provided are systems for tractoring in a wellbore in accordance with thedisclosure and the illustrated FIGS. An example system comprises adownhole tractor comprising a tractor wheel comprising: a series ofcontinuous springs disposed on the circumference of the tractor wheel,wherein the individual continuous springs in the series of continuoussprings are separated by a gap, and a void disposed on the interior ofthe tractor wheel and that is continuous about the circumference of thetractor wheel; and a conduit disposed in the wellbore; wherein thetractor wheel is configured to contact the surface of the conduit;wherein the conduit comprises an open hole portion of the wellbore, acasing, or a tubing.

Additionally or alternatively, the system may include one or more of thefollowing features individually or in combination. The tractor wheel mayfurther comprise a series of discontinuous springs disposed on theinterior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother. The void may be filled with a filler material comprising arubber, a rubber and metal composite, or any combination thereof. Thevoid may be a first void; and wherein the tractor wheel furthercomprises a second void disposed between the series of continuoussprings and the series of discontinuous springs. The first void may befilled with a filler material comprising a rubber, a rubber and metalcomposite, or any combination thereof. The tractor wheel may furthercomprise a series of discontinuous springs; wherein the individualcontinuous springs in the series of continuous springs alternate withthe individual discontinuous springs in the series of discontinuoussprings; wherein at least a portion of the continuous springs arecoupled to a body of the tractor wheel. The tractor wheel may furthercomprise a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in the open bend of each adjacent backward-facing raised curve;wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.The tractor wheel may further comprise a tread comprising a continuousserpentine-shaped raised curve with raised posts disposed in each openbend. The wellbore may comprise a conduit; wherein the tractor wheelcontacts the surface of the conduit; wherein the conduit comprises anopen hole portion of the wellbore, a casing, or a tubing. The tractorwheel may further comprise a series of discontinuous springs disposed onthe interior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother; wherein the void is a first void; and wherein the tractor wheelfurther comprises a second void disposed between the series ofcontinuous springs and the series of discontinuous springs. The tractorwheel may further comprise a series of discontinuous springs; whereinthe individual continuous springs in the series of continuous springsalternate with the individual discontinuous springs in the series ofdiscontinuous springs; and wherein at least a portion of the continuoussprings are coupled to a body of the tractor wheel. The void may befilled with a filler material comprising a rubber, a rubber and metalcomposite, or any combination thereof. The tractor wheel may furthercomprise a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in the open bend of each adjacent backward-facing raised curve;and wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.The tractor wheel may further comprise a tread comprising a continuousserpentine-shaped raised curve with raised posts disposed in each openbend.

The preceding description provides various examples of the systems andmethods of use disclosed herein which may contain different method stepsand alternative combinations of components. It should be understood thatalthough individual examples may be discussed herein the presentdisclosure covers all combinations of the disclosed examples, including,without limitation, the different component combinations, method stepcombinations, and properties of the system. It should be understood thatthe compositions and methods are described in terms of “comprising,”“containing,” or “including” various components or steps. Thecompositions and methods can also “consist essentially of” or “consistof the various components and steps.” Moreover, the indefinite articles“a” or “an,” as used in the claims, are defined herein to mean one ormore than one of the element that it introduces.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited. In the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range are specifically disclosed. Inparticular, every range of values (of the form, “from about a to aboutb,” or, equivalently, “from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to setforth every number and range encompassed within the broader range ofvalues even if not explicitly recited. Thus, every point or individualvalue may serve as its own lower or upper limit combined with any otherpoint or individual value or any other lower or upper limit, to recite arange not explicitly recited.

One or more illustrative examples incorporating the examples disclosedherein are presented. Not all features of a physical implementation aredescribed or shown in this application for the sake of clarity.Therefore, the disclosed systems and methods are well adapted to attainthe ends and advantages mentioned, as well as those that are inherenttherein. The particular examples disclosed above are illustrative only,as the teachings of the present disclosure may be modified and practicedin different but equivalent manners apparent to those skilled in the arthaving the benefit of the teachings herein. Furthermore, no limitationsare intended to the details of construction or design herein shown otherthan as described in the claims below. It is therefore evident that theparticular illustrative examples disclosed above may be altered,combined, or modified, and all such variations are considered within thescope of the present disclosure. The systems and methods illustrativelydisclosed herein may suitably be practiced in the absence of any elementthat is not specifically disclosed herein and/or any optional elementdisclosed herein.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the following claims.

What is claimed is:
 1. A tractor wheel for a downhole tractor, thetractor wheel comprising: a series of continuous springs disposed on thecircumference of the tractor wheel, wherein the individual continuoussprings in the series of continuous springs are separated by a gap, anda first void disposed on the interior of the tractor wheel and that iscontinuous about the circumference of the tractor wheel; a series ofdiscontinuous springs disposed on the interior of the tractor wheel;wherein each discontinuous spring is discontinuous in that it comprisestwo separate members that face each other; and wherein the tractor wheelfurther comprises a second void disposed between the series ofcontinuous springs and the series of discontinuous springs.
 2. Thetractor wheel of claim 1, wherein the first void is filled with a fillermaterial comprising a rubber or a rubber and metal composite.
 3. Thetractor wheel of claim 1, wherein the second void is filled with afiller material comprising a rubber or a rubber and metal composite. 4.The tractor wheel of claim 1, further comprising a series ofdiscontinuous springs; wherein the individual continuous springs in theseries of continuous springs alternate with the individual discontinuoussprings in the series of discontinuous springs; wherein at least aportion of the continuous springs are coupled to a body of the tractorwheel.
 5. The tractor wheel of claim 4, wherein the first void is filledwith a filler material comprising a rubber or a rubber and metalcomposite.
 6. The tractor wheel of claim 1, further comprising a treadcomprising a series of alternating forward-facing raised curves andbackward-facing raised curves having terminal ends; wherein the terminalends of each forward-facing raised curve is disposed in an open bend ofeach adjacent backward-facing raised curve; wherein the terminal ends ofeach backward-facing raised curve is disposed in the open bend of eachadjacent forward-facing raised curve.
 7. The tractor wheel of claim 1,further comprising a tread comprising a continuous serpentine-shapedraised curve with raised posts disposed in each open bend.
 8. A methodfor tractoring in a wellbore, the method comprising: providing adownhole tractor comprising a tractor wheel comprising: a series ofcontinuous springs disposed on the circumference of the tractor wheel,wherein the individual continuous springs in the series of continuoussprings are separated by a gap, a first void disposed on the interior ofthe tractor wheel and that is continuous about the circumference of thetractor wheel; and a series of discontinuous springs disposed on theinterior of the tractor wheel; wherein each discontinuous spring isdiscontinuous in that it comprises two separate members that face eachother; and wherein the tractor wheel further comprises a second voiddisposed between the series of continuous springs and the series ofdiscontinuous springs introducing the downhole tractor into thewellbore; and propelling the downhole tractor in the wellbore.
 9. Themethod of claim 8, wherein the wellbore comprises a conduit; wherein thetractor wheel contacts the surface of the conduit; wherein the conduitcomprises an open hole portion of the wellbore, a casing, or a tubing.10. The method of claim 8, wherein the tractor wheel further comprises aseries of discontinuous springs; wherein the individual continuoussprings in the series of continuous springs alternate with theindividual discontinuous springs in the series of discontinuous springs;and wherein at least a portion of the continuous springs are coupled toa body of the tractor wheel.
 11. The method of claim 8, wherein the voidis filled with a filler material comprising a rubber or a rubber andmetal composite.
 12. The method of claim 8, wherein the tractor wheelfurther comprises a tread comprising a series of alternatingforward-facing raised curves and backward-facing raised curves havingterminal ends; wherein the terminal ends of each forward-facing raisedcurve is disposed in an open bend of each adjacent backward-facingraised curve; and wherein the terminal ends of each backward-facingraised curve is disposed in the open bend of each adjacentforward-facing raised curve.
 13. The method of claim 8, furthercomprising a tread comprising a continuous serpentine-shaped raisedcurve with raised posts disposed in each open bend.
 14. The method ofclaim 8, wherein the downhole tractor is coupled to a wireline disposedin the wellbore.
 15. A system for tractoring in a wellbore, the systemcomprising: a downhole tractor comprising a tractor wheel comprising: aseries of continuous springs disposed on the circumference of thetractor wheel, wherein the individual continuous springs in the seriesof continuous springs are separated by a gap, a first void disposed onthe interior of the tractor wheel and that is continuous about thecircumference of the tractor wheel; and a series of discontinuoussprings disposed on the interior of the tractor wheel; wherein eachdiscontinuous spring is discontinuous in that it comprises two separatemembers that face each other; and wherein the tractor wheel furthercomprises a second void disposed between the series of continuoussprings and the series of discontinuous springs; and a conduit disposedin the wellbore; wherein the tractor wheel is configured to contact thesurface of the conduit; wherein the conduit comprises an open holeportion of the wellbore, a casing, or a tubing.
 16. The system of claim15, wherein the tractor wheel further comprises a series ofdiscontinuous springs; wherein the individual continuous springs in theseries of continuous springs alternate with the individual discontinuoussprings in the series of discontinuous springs; and wherein at least aportion of the continuous springs are coupled to a body of the tractorwheel.
 17. The system of claim 15, wherein the tractor wheel furthercomprises a tread comprising a series of alternating forward-facingraised curves and backward-facing raised curves having terminal ends;wherein the terminal ends of each forward-facing raised curve isdisposed in an open bend of each adjacent backward-facing raised curve;and wherein the terminal ends of each backward-facing raised curve isdisposed in the open bend of each adjacent forward-facing raised curve.18. The system of claim 15, wherein the void is filled with a fillermaterial comprising a rubber or a rubber and metal composite.
 19. Thesystem of claim 15, wherein the tractor wheel further comprises a treadcomprising a continuous serpentine-shaped raised curve with raised postsdisposed in each open bend.
 20. The system of claim 15, wherein thedownhole tractor is coupled to a wireline disposed in the wellbore.